Process for the catalytic production of anhydrous stannic chloride



Nov. 28,- 1933. J O r AL 1,937,419

PROCESS FOR THE CATALYTIC PRODUCTION OF ANHYDROUS STANNIC CHLORIDE Filed June 15, 1932 IJIII'II Sl'annic Qhloride 1 MoHenTin and Anfimory w INVENTORSI ATTORNEYS.

Patented Nov. 28, 1933 S PATENT OF FiCE PROCESS FGR THE CATALYTIC PRODUC- TION OF ANHYDROUS STANNIC CHlLO RIDE Jacques Wolf, Nice, and Georges Andr Fayre, Lyon, France Application June 15, 1932. Serial No. 617,402 16 mass. (@1. 23-98) For obtaining anhydrous stannic chloride, it has already been proposed to send chlorine, through a tube, into the midst of a mass of molten tin. Y

But it is not possible to obtain in this way anhysame time stannous chloride.

In fact, tin has a great avidity for chlorine, and

it deprives the stannic chloride formed of two of its atoms of chlorine, to produce stannous chloride.

Now, the presence of stannous chloride with stannic chloride is a very serious inconvenience, because it causes great difliculties in theoperation, and such losses in yield that the above mentioned process cannot with advantage be commercially carried out. 7 a

For obtaining pure stannic chloride, without any trace of stannous chloride, it has been proposed to chlorinate tin at a low temperature, that is to drous stannic chloride without obtaining at the say under a solid form, by exposing it to the action either of a gaseous bath of chlorine, or of a liquid bath of stannic chloride supersaturated with chlorine. In this way, the surface of metallic tin is always in contact with a medium supersaturated with chlorine, and the stannic chloride formed, having no action whatever on the solid metal, is condensed in the liquid state.

The present invention consists in another process for the production of anhydrous stannic chloride without formation of stannous chloride, from molten tin,: or from a molten mixture of tin and other metals.

The applicants have discovered, after having studied for several years the mutual action of metallic chlorides, either on each other, or in presence of their metals or of complex alloys of metals other than those from which they issue, certain new properties of antimony, antimony pentachloride and antimony trichloride, relatively to tin, stannous chloride and stannic chloride.

The applicants have found that antimony pentachloride immediately converts molten tin, not into stannous chloride, but into stannic chloride, whereas antimony. trichloride has little affinity for metallic tin, but instantaneously converts stannous chloride into stannic chloride, for returning to the state of metallic antimony.

By applying this property to the chlorination of tin, the applicants have discovered the continuous catalytic propertiesof antimony with respect to tin and its chlorides, during chlorination at melting temperature and above this temperature.

The present invention therefore consists in mixing in a mass of molten tin a given quantity of metallic antimony, the quantity of which must not be less than about 5%, and in causing chlorine to act at the surface or at one or more points of this molten surface. 'The combustion is immediate,'giving rise to an intense evolution of heat, and stannic chloride and antimony pentachloride are The latter, at this temperature, is in an unstable condition in which it acts as catalyst, yielding its chlorine for producing stannic chloride, and taking the more stable form of trichloride; but trichloride immediately acts on the stannous chloride which is formed by contact with the metal and'stannic chlorides, by rec tifying the decomposition and bringing back stannous chloride to stannic chloride, giving up its chlorine to the latter in order to be restored to metallic antimony. This metallic antimony is immediately re-chlorinated to form pentachloride and'begins its cycle over again until all'the tin has been chlorinated into stannic chloride, then it eliminates itself in the form of antimony chloride.

It is to be understoodthat instead of using metallic antimony, antimony pentachloride or trichloride might quite as well be directly employed,

in a minimum proportion equivalent to 5% of the weight of metal treated.

The stage at which antimony chlorinates by itself is immediately seen by the sudden rise of temperature which arises from the very intense exothermic reaction of chlorine with metallic antimony.

The adjunction of other metals to tin does not hinder in anyway the catalytic action of antimony; the operation progresses as regularly, in case antimony is added to a molten mixture of tin and copper, of tin and bismuth, of tin and lead, or to ternary mixtures: lead-copper-tin, lcad-bismuth-tin, or to any mixtures of complex alloys 'such as lead-tin-bismuth-nickel-coppr.

As soon as the minimum" quantity of antimony, or of its chlorides, is added to one of these alloys, as indicated, the chlorination of tin forms free'anhydrous stannic chloride, which is free from any'stannous chloride. Above 5% antimony can be added in any quantity.

The presence in an alloy of a major proportionof lead activates the property of antimony and allows of diminishing the minimum limit of the proportion of antimony or of its chlorides from 5% down to 3%. This phenomenon canbe easilyexplaine'd: lead chloride being liquid at 600 0., condenses as soon as the combustion has been effected and forms a protecting surface for the stannic chloride already formed. 'Antimony chloride acts at this moment by catalyzing the tin converted into stannous chlorideby the law of equilibrium which is always maintained between the lead chloride formed and pure tin.

The accompanying drawing diagrammatically illustrates, by way of example only, a form of construction of an apparatus for carrying the invention into practice.

The single figure of the drawing is an elevation in axial section.

The apparatus is composed of a closed chamber 1, for instance of cylindrical shape, within which is arranged a partition 2, for instance concentric with the said chamber, which divides the inner space into two parts A and B communicating together at their base, as illustrated.

Molten tin is contained in these, chambers A and B; the melting of the tin is initially obtained and maintained by an external source of heat, which it has not been deemed necessary to illustrate. But, from the beginning of the operation, the quantity of heat given ofi by the latter is such that heating of the apparatus becomes unnecessary.

The chamber A is connected, by a pipe 3, to the chlorine inlet. Chlorine expands within the chlorination chamber A at a temperature higher than 250 C. and which can reach 700 C. The combustion takes place at the surface of the liquid bath in the chamber A, by simultaneously producing antimony pentachloride and stannic chloride.

These two latter compounds enter the chamber B by passing under the partition 2; stannic chloride alone reaches the surface of the bath in the chamber B, whilst antimony which has again become metallic passes to the lower part of the vessel.

,The stannic chloride issues through the'pipe 4' and passes to open air condensers (which it has not been deemed necessary to illustrate) and does not therefore remain in contact with the surface of the molten tin.

l is obvious that other apparatus might be used for carrying the invention into practice, and it is to, be understood that, for utilizing the present process, the invention is not limited to the apparatus previously described which is given only by way of example. What we claim as our invention and desire to secure by Letters Patent is:'- 1. 'In a processfor the treatment of molten tin with chlorine, the mixing therewith of antimony to act as catalyst, in a minimum proportion of 5%,of the weight of tin treated, for obtaining anhydrous stannic chloride without stannous chloride.

2. In a process forthe treatment, with chlorine, of molten tin mixed with metals other than lead, the mixing therewith of antimony to act as catalyst, in a minimum proportion of I 5% of the weight of metal treated, forobtaining anhydrous stannic chloride without stannous chloride.

3. In a process for the treatment, with chlorine, of molten tin mixed with lead, the mixing therewith of antimony to act as catalyst, in a minimum proportion of 3% of the weight of metal treated, for obtaining anhydrous stannic chloride without stannous chloride.

4. In a process for the treatment, with chlorine, of molten tin mixed with other metals and with lead,.fthe mixing therewith of antimony to act as catalyst, in a minimum proportion of 3% of the weight of metal treated, for obtaining anhydrous stannic chloride without stannous chloride.

5. ,In a process for the treatment of molten tin with chlorine, the mixing therewith of antimony pentachloride to act as catalyst for obtaining anhydrous stannic chloride without stannous chloride.

6. In a process for the treatment of molten tin with chlorine, the mixing therewith of antimony pentachloride to act as catalyst, in a minimum proportion of metallic antimony equivalent to 5% of the weight of tin treated, for obtaining anhydrous stannic chloride without stannous chloride.

7. In a process for thetreatment, with chlorine, of molten tin mixed with other metals, the mixing therewith or antimony pentachloride to act as catalyst for obtaining anhydrous stannic chloride without stannous chloride.

8. In a process for the treatment, with chlorine, of molten tin mixed'with metals other than lead, the'mixing therewith of antimony pentachloride to act as catalyst, in aminimum proportion of metallic antimony equivalent to 5% of the weight of metal treated, for obtaining anhydrousstannic chloride without stannous chloride.

9. In a process for the treatment, with chlorine, of molten tin mixed with lead, the mixing therewith of antimony pentachloride to act as cataiyst, in a minimumproportion of metallic antimony equivalent to 3% of the weight of metal treated, for obtaining anhydrous stannic chloride without stannous chloride;

10. In a process for the treatment, with chlorine, of molten tin mixed with other metals and with lead, the mixing therewith of antimony pentachloride to act as catalyst, 'in a minimum proportion of metallic antimony equivalent to 3% of the weight of metal treated, for obtaining an hydrous stannic chloride without stanncus chloride.

11. In a process for the treatment of molten tin with chlorine, the mixing therewith of antimony trichloride to act as catalyst for obtaining anhydrous stannic chloride without Stan-nous chloride.

12. In a process for the treatment of molten tin with chlorine, the mixing therewith of antimony trichloricle to act as catalyst, in a minimum proportion of metallic antimony equivalent to 5% of the weight of tin treated, for obtaining anhydrous stannic chloride without stannous chloride.

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. 13. In a process for the treatment, with chlorine, of molten tin mixed with other metals, the mixing therewith of antimony tric'hlori'de to act as catalyst for obtaining anhydrous stannic chloride without stannous chleride.

, l i. In a process for the treatment, with chlorine, of molten tin mixed with metals other than lead, the mixing therewith'of antimony trichlo-' ride'to act as catalyst, in a minimum proportion of metallic antimony equivalent to 5% of the weight of metal treated, for obtaining anhydrous stannic chloride without stannous chloride.

15. In a process for the treatment, with chlorine, of molten tin mixed with lead, the mixing therewith of antimony trichloride to act as catalyst, in aminimum proportion of metallic antimony equivalent to 3% of the weight of metal treated, for obtaining anhydrous stannic chloride without stannous chloride.

16. In a process for the treatment, with'chlorine, of molten tin mixed with other metals and with lead, the mixing therewith of antimony trichloride to act as catalyst, in a minimum proportion of metallic antimony equivalent to 3% of the weight of metal treated, for obtaining an- GEORGES AN RE: FAVRE. 

